This invention relates to a method of and apparatus for connecting the attachment part of a tear-off section of a sealing cap and a pulling member for removing the tear-off section. A sealing cap of this type is described in my copending application Ser. No. 119,103, filed Nov. 10, 1987.
Tear-off sealing caps in various forms have enjoyed considerable commercial success, primarily due to the ease with which the consumer can remove the cap from a bottle without having to use a special bottle opener. One typical version of tear-off sealing cap is provided with a pulling member in the form of a metal ring which is secured to an attachment part or tongue on the tear-off section. In this version, the attachment part is connected to the metal ring by being rolled into or around a ring using a special tool. This method of attachment is relatively complicated and is carried out using expensive machinery which is subject to considerable wear. Furthermore, it is difficult to achieve the desired high and uniform strength in the connection between attachment part and the ring.
The choice of material used in prior art sealing caps is also limited by the prior art methods. Steel, which has a tendency to rust, has been the principal and most practical material. Tear-off sealing caps of other materials, such as aluminum, have been manufactured by punching blanks from sheet material, but such techniques are inefficient because they waste considerably more material than sealing caps made according to the invention.
When manufacturing the pulling member by conventional techniques, it is difficult to make it sufficiently thick and of a convenient shape for gripping, since the materials available and the ways of shaping it are limited. Conventional tear-off sealing caps also entail risk of injury when opening the cap, particularly cuts caused by sharp edges if the cap is opened incorrectly.